Your basic screening is whatever you do in order to assure yourself that the potential client is not LE. You can use a work number, call it, and ask for the client. This would also mean the client tells you his name.

As for screening for potential threat, that is something I think you have to just use a gut feeling for. First check the blacklist sites for providers, many listings of clients that other providers have blacklisted and the reasoning why.

terrev has good ideas, find a well known provider in your area and pick her brain for a little bit. I wouldn't think any provider would have a problem with answering a couple questions from a new girl.

b-

access to that board yet, contact a few providers in your area to seek their advice.  There will be guys who want to see you without giving any information--this is not good.  You need to look out for YOUR safety before considering anything else.  There are some real wackoos out there; be cautious and let your gut (intellect if you prefer) guide you.